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Create unique External Alarm Configurations for each area.

The Silence All verb will of course silence ”all”, but you can just as simple write ”0” or ”false” straight to the OPC property from a push button, PG2 Property Writer or Simple Scripting verb (=hotkey).

From the Release Notes for System Version 6.0.3.2:
The security settings do not affect the External Alarm Configuration aspects, resulting in any user silencing the external alarms! This problem has been resolved!

How to make security settings so only one specific user can silence one specific Ext Alarm?
Is it done on the object controlled from the Ext Alarm?